Romex NMC inside Metal Armor

[bobinyelm]

With regard to residential wiring (in a garage), It's apparently "legal" to run Romex NMC through PVC conduit for "physical protection" in places where it might be damaged (below 8ft height in garages or shops, for instance).

But where one needs to run wiring externally around corners and it needs physical protection, can it be enclosed in flexible armor (plastic or metal).

They obviously sell "BX" type armor and flexible conduit in various diameters, but is it ONLY OK to use individual pulled wires in it, then transition to NMC in a junction box (when in an area physical protection is not required) and continue with NMC, or alternatively wire the whole building using individual wires and use conduit or armor for the installation? Or can a portion of armor be slipped over the Romex (properly terminated at each end) to protect the NMC where it is exposed to damage?

This is in an older (1945) home where a new 240v circuit is being run to the attached garage. There is already an armored cable that was previously installed and certified (inspected and has a city inspection placard posted) that is surface mounted leading from the panel to a drier outlet. The new circuit would be run right next to the existing armored cable, and extend to the adjoining garage.

 

[wyliesdiesels]

What do you mean by externally? Do you mean outdoors?

Nm-b is not permitted for use outside.

And i would never put nm-b in FMC. Thats a pain in the ***.

 

[mike93lx]

BX isn't "armor" and is subject to the same damage restrictions as NM-B, IIRC.

 

[Norcal]

BX isn't "armor" and is subject to the same damage restrictions as NM-B, IIRC.

"BX" has the conductors factory installed, steel, or aluminum, flex (Greenfield) does not but is still not protection either.

 

[bobinyelm]

BX isn't "armor" and is subject to the same damage restrictions as NM-B, IIRC.

So using BX (armored) cable inside a building offers no advantage legally or physically over the bare Romex? If Romex is not legal, then BX/Armored is also illegal?

So I must use rigid PVC or EMT to provide physical protection below 8ft in height above a floor?

Bob

 

[bobinyelm]

What do you mean by externally? Do you mean outdoors?

Nm-b is not permitted for use outside.

And i would never put nm-b in FMC. Thats a pain in the ***.

No, by "externally" I means surface-mounted on a wall in a residential setting where it is not possible to route the wire THROUGH the wall.

In addition, the wire must "snake" around obstructions along its path before it can make its way to the 8ft height where it can be unprotected, making rigid EMT/PVC Conduit impractical.

Since a portion of the wire will be positioned at less than 8ft above floor level, it must be physically protected from damage.

In my shop, the inspector was OK with Romex inside PVC. I was asking if it's "legal" to use the "empty" spiral metal armor they sell to likewise protect the segment of the NMC circuit before it is routed above the 8ft ceiling where it can simply be stapled to the framing.

You say you would never do this because it is a PITA, but I tied routing 10-2 w/gnd through the spiral metal armor and over the short distance involved, it wasn't bad.

If it IS legal to route Romex through such amoring (See https://www.homedepot.com/p/AFC-Cabl...-AFC/205070934 ) where the NMC enters or exits the armor (and is not required to be "protected") do you insert one of these of the appropriate size in the end of the armor so the Romex insulation is not cut/chaffed?
https://www.homedepot.com/p/3-8-in-...MC-Anti-Short-Bushing-35-Pack-75401/100170558

 

[bobinyelm]

"BX" has the conductors factory installed, steel, or aluminum, flex (Greenfield) does not but is still not protection either.

So you are saying that the metal sheathed cable (I guess it's called Greenfield"?) must be routed through conduit to be considered 'protected?" (Not that that is probably legal).

This is what I am referring to, but I gather it's not legally considered "conduit" (does not meet electrical codes) though they call it conduit?

https://www.homedepot.com/p/AFC-Cab...exible-Aluminum-Conduit-5602-22-AFC/205070934

I admit to being confused... The electrical inspector unfortunately won't take questions ("I am an inspector, not an educator."), so I am asking here.

Bob

 

[Muzzy]

If you want to strictly obey NEC, don't use it. The spec. sheet for what you posted indicates that it is rated as FMC, which is not allowed where subject to physical damage.

348.12 Uses Not Permitted. FMC shall not be used in the
following:
(1) In wet locations
(2) In hoistways, other than as permitted in 620.21(A)(1)
(3) In storage battery rooms
(4) In any hazardous (classified) location except as permitted
by other articles in this Code
(5) Where exposed to materials having a deteriorating effect
on the installed conductors, such as oil or gasoline
(6) Underground or embedded in poured concrete or aggregate
(7) Where subject to physical damage

 

[AntonLargiader]

So using BX (armored) cable inside a building offers no advantage legally or physically over the bare Romex?

Physically, yes it does. It won't be eaten by mice and is less likely to be nicked by sharp edges or punctured by a nail.

 

[rabidsquirrel]

So you are saying that the metal sheathed cable (I guess it's called Greenfield"?) must be routed through conduit to be considered 'protected?" (Not that that is probably legal).

This is what I am referring to, but I gather it's not legally considered "conduit" (does not meet electrical codes) though they call it conduit?

https://www.homedepot.com/p/AFC-Cab...exible-Aluminum-Conduit-5602-22-AFC/205070934

I admit to being confused... The electrical inspector unfortunately won't take questions ("I am an inspector, not an educator."), so I am asking here.

Bob

Those are two different things. Greenfield (fmc) does not need to be protected, it's in the same class as pipe. BX, MC, AC cable are different, and need to be protected when surface mounted below 8'.

Sent from my VS987 using Tapatalk

 

[Norcal]

Those are two different things. Greenfield (fmc) does not need to be protected, it's in the same class as pipe. BX, MC, AC cable are different, and need to be protected when surface mounted below 8'.

Sent from my VS987 using Tapatalk

If you want to strictly obey NEC, don't use it. The spec. sheet for what you posted indicates that it is rated as FMC, which is not allowed where subject to physical damage.

348.12 Uses Not Permitted. FMC shall not be used in the
following:
(1) In wet locations
(2) In hoistways, other than as permitted in 620.21(A)(1)
(3) In storage battery rooms
(4) In any hazardous (classified) location except as permitted
by other articles in this Code
(5) Where exposed to materials having a deteriorating effect
on the installed conductors, such as oil or gasoline
(6) Underground or embedded in poured concrete or aggregate
(7) Where subject to physical damage

Greenfield (FMC) is subject to the same restrictions as NM,AC,MC as to protection from physical damage.

 

[rabidsquirrel]

Greenfield (FMC) is subject to the same restrictions as NM,AC,MC as to protection from physical damage.

So when greenfield is used from a junction box or pipe to a peckerhead on a motor it needs to be protected?

Sent from my VS987 using Tapatalk

 

[bobinyelm]

Physically, yes it does. It won't be eaten by mice and is less likely to be nicked by sharp edges or punctured by a nail.

That makes sense, but...

Here is the plan. It's a single story ranch house with an attached garage. All the described wiring will be inside either the laundry room or the garage (which share a common wall).

The main panel for the home is in the laundry room, and the room is sheathed with 1/2" CDX plywood from many years ago (house built 1945), so the plan was to surface-mount FMC that would penetrate the wallboard, then pass through an Anti-Short Bushing inside the wall cavity ( https://images.homedepot-static.com...743a22/svn/conduit-fittings-75403-64_1000.jpg ), and through a Romex clamp into the service panel and on to the breaker. FMC would allow the wire to conform to wall obstructions and gentle bends where necessary.

The other end of that new circuit would continue to run on the surface of the laundry room wall next to an existing surface-mounted FMC that has Romex inside terminating in a surface-mounted drier outlet (it was previously installed by a professional electrician, and inspected/placarded by the City Inspector) , then it would penetrate/pass-thru a wall separating the laundry room from the attached garage, and run a couple of feet on the surface of the interior garage wall (more CDX wall board), then turn vertical until it is above the 8ft level where it no longer needs protection, pass through another Anti Short Bushing, and run "bare Romex" above the open ceiling framing of the garage for about 25ft to a vertical drop passing through rigid NM PVC conduit to a plastic outlet box with a 6-30 receptacle in it (conduit and box would be mounted on an existing stud since that portion of the garage is open-stud construction still.

Does that sound like it would meet code?

Trying to use rigid conduit from the service panel across the laundry room wall, though the wall into the garage, and up that wall would be extremely complicated compared to the ease of using FMC assuming FMC is "legal".

Obviously using FMC as I propose WAS legal at the time the drier circuit was installed and passed by the City Inspector, but I know codes can change, so I am asking if what I am describing is STILL code-acceptable.

Thanks-
Bob

 

[alfredeneuman]

then pass through an Anti-Short Bushing inside the wall cavity ( https://images.homedepot-static.com...743a22/svn/conduit-fittings-75403-64_1000.jpg

Obviously using FMC as I propose WAS legal at the time the drier circuit was installed and passed by the City Inspector, but I know codes can change, so I am asking if what I am describing is STILL code-acceptable.
Bob

The picture is for an anti-short bushing in MC Cable(although it's not required), AC cable, & 3/8" flex.

The armor of all metal flex of the '40s, was made of very heavy galvanized steel. It was a ***** to cut, even with a hacksaw.
Today they produce reduced wall steel and aluminum flex, which the armor can be snapped, and easily cut with tin snips.

 

[AntonLargiader]

In this thread no one is talking about how that flexible conduit isn't legal for exposed locations. Maybe someone will explain why you couldn't do that in your situation. :shrug

 

[bobinyelm]

In this thread no one is talking about how that flexible conduit isn't legal for exposed locations. Maybe someone will explain why you couldn't do that in your situation. :shrug

Agree-

When I wired my shop last year the State Inspector (not city as I live in the county) said I could use my choice of rigid metallic, plastic OR FMC below 8ft level in my shop.

The state inspectors will let you drop in and ask questions about code or methods as well, unlike the city inspectors. That was handy.

I used plastic for fixed wall-attached protection, but used FMC where the cable was "hanging in the air" (like going from the box on the wall to the lift, and from the box to my compressor).

Not sure if in residential you need RIGID conduit, whereas in shop buildings you can use FMC for protection?

Maybe someone will weigh in.

Bob

 

[alfredeneuman]

In this thread no one is talking about how that flexible conduit isn't legal for exposed locations. :shrug

That thread was some really messed up work that was already installed and the violations were just too numerous to list.
Nobody said it was OK if you read the thread closely.

We're just trying to prevent the same situation from happening ahead of time.

 

[Firebrick43]

Why not skip all the laundry room obstructions? Use Emt to go through the ceiling, across the trusses in the attic and drop down in the garage?

 

[bobinyelm]

Why not skip all the laundry room obstructions? Use Emt to go through the ceiling, across the trusses in the attic and drop down in the garage?

Interesting idea. I like it, though when I said it was a ranch, there is ONE room tucked like a bonus room over the laundry room (but not over the garage).

Plus, the garage is offset by about 10ft from the service panel, so going up would not give access to above the garage, unfortunately.

My described plan is to go laterally from the service panel to where it can turn 90 deg and thru the common wall into the garage, then up to the open space above the garage ceiling where you suggest, albeit in a much less convenient manner.

 

[TRWham]

In this thread no one is talking about how that flexible conduit isn't legal for exposed locations. Maybe someone will explain why you couldn't do that in your situation. :shrug

FMC and NM are both explicitly LEGAL in the NEC for exposed work. FMC must not be "subject to physical damage" and NM must be "protected from physical damage." What "subject to physical damage" means is not addressed in NFPA 70, so it is up to interpretation. The interpretation that counts is the one by the inspector, but FMC properly secured to the wall of a laundry room seems pretty safe from physical damage to me.

 

[bobinyelm]

FMC and NM are both explicitly LEGAL in the NEC for exposed work. FMC must not be "subject to physical damage" and NM must be "protected from physical damage." What "subject to physical damage" means is not addressed in NFPA 70, so it is up to interpretation. The interpretation that counts is the one by the inspector, but FMC properly secured to the wall of a laundry room seems pretty safe from physical damage to me.

Perhaps that's why one poster mentioned it is NOT legal since it offers limited protection from some types of physical damage.

The FMC would be at 5ft above thye floor where it would exit the wall near the main panel, rising to 7ft above the floor where it runs along the wall for the rest of its run, so I agree it would face minimal physical damage potential.

As you say, it will be up to the inspector. It would seem much simpler to be able to ask the inspector in advance (as I can with the State Inspector) if an installation will meet his approval, but I guess if he disapproves it, it can be ripped out and done another way. It is likely if he is on-site and disapproves the FMC he will probably suggest a method he deems acceptable.

As I mentioned, the new FMC will run next to the existing FMC feeding the drier outlet (that FMC runs at 7ft level then turns down to a surface mounted drier receptacle 12" above the floor), though the new one will continue an additional 8ft or so and penetrate a wall before going up above the garage ceiling joists (where it doesn't require physical protection), though the drier FMV was inspected/approved several years back and inspectors/codes change.

I feel confident enough now (via helpful comments here) to take a chance at least using my proposed method and routing and hope for a successful inspection.

I will be fixing some of the grievous electrical code violations that presently exist presently in the garage before calling for an inspection so as to put the inspector in a better mood.

It's amazing to see the botch jobs done over a 70 year period by past owners and renters. Almost half the 8 outlets in the garage have reversed polarity, none of the grounding outlets have grounds, and some are 20a outlets on 15a circuits, and a few actually had the unused outlet contact screws extending out far enough they were touching/energizing the metal box itself to 120v potential to ground (since the boxes were ungrounded, nothing tripped, but someone in poorly insulated shoes on the damp concrete floor would have gotten a nasty shock touching the exposed boxes). That's just a sampling. My understanding is the inspector will turn a blind eye toward any past botch jobs, but I don't feel good leaving them in place.

Thanks,
Bob

 

[rjcnaples]

You can use “Flex metal conduit” inside surfaced mounted as long as it isn’t exposed to moisture. And yes you would think it is ok to put NMC inside for protection of the cable. I use to for years with no issues.
But now the inspectors want individual conductors sized according to circuit to be installed. I’m mean hots, neutral, ground. Not NMC.

We use to stub out say 6-8’ of NMC When we roughed in for pumps, AC units, etc. And the at trim out time. Set ( mount) disconnects take the left over tail and slide it through say Pvc, or liquid tight and make the connection to the equipment. And never had a issue ever. But now it has become a issue.
We now use the same Pvc liquid tight but have to install individual conductors for equipment make up.

For your job.
I would use “flex” up high with individual conductors installed, hit the junction boxs to make the transition and then come down with hard conduit with individual conductors

If you already purchase the NMC just strip off the outer jacket and use the conductors

Were I live they charge for failed inspections its a money-making cash cow for the building department.


Sent from my iPhone using Tapatalk

 

[alfredeneuman]

If you already purchase the NMC just strip off the outer jacket and use the conductors

That would technically be a Code violation because the individual conductors aren't labelled.
The labeling is on the jacket.

 

[bobinyelm]

You can use “Flex metal conduit” inside surfaced mounted as long as it isn’t exposed to moisture. And yes you would think it is ok to put NMC inside for protection of the cable. I use to for years with no issues.
But now the inspectors want individual conductors sized according to circuit to be installed. I’m mean hots, neutral, ground. Not NMC.

We use to stub out say 6-8’ of NMC When we roughed in for pumps, AC units, etc. And the at trim out time. Set ( mount) disconnects take the left over tail and slide it through say Pvc, or liquid tight and make the connection to the equipment. And never had a issue ever. But now it has become a issue.
We now use the same Pvc liquid tight but have to install individual conductors for equipment make up.

For your job.
I would use “flex” up high with individual conductors installed, hit the junction boxs to make the transition and then come down with hard conduit with individual conductors

If you already purchase the NMC just strip off the outer jacket and use the conductors

Were I live they charge for failed inspections its a money-making cash cow for the building department.


Sent from my iPhone using Tapatalk

I guess as long as the inspector doesn't examine the individual wires for marking, it sounds like a plan. I seriously doubt he will.
(I didn't read alfredenewman's post until after I raised the question, but my guess would be he won't look for THHN markings on individual wires, but then the ground is a bare wire in NMC, and an individual ground would be green THHN, yes? THAT he would notice I suspect.

We DID buy the NMC, but most of the run is NMC OK.

The state inspector last year was perfectly OK w/ NMC inside rigid PVC since the only reason for conduit was protection below ft, but that's no guaranty that this guy will.

I suspected that money aspect of inspections could be the reason that they don't answer questions. More chances for mistakes and failures (failed inspections) and more fees.

Thanks,
Bob

I did a bunch of searches for "NMC in Conduit" and got lots of opinions both ways.
It seems there are people lined up on both sides of the question.

Found this, but not sure if it controls or not-

Article 334 NM Cable

334.15 Exposed Work. In exposed work, except as provided
in 300.11(A), cable shall be installed as specified in
334.15(A) through (C).
(A) To Follow Surface. Cable shall closely follow the surface
of the building finish or of running boards.
(B) Protection from Physical Damage. Cable shall be
protected from physical damage where necessary by rigid·
metal conduit, intermediate metal conduit, electrical metallic
tubing, Schedule 80 PVC conduit, or other approved
means. Where passing through a floor, the cable shall be
enclosed in rigid metal conduit, intermediate metal conduit,
electrical metallic tubing, Schedule 80 PVC conduit, or
other approved means extending at least 150 mm (6 in.)
above the floor

 

[wyliesdiesels]

This dead-horse has been beaten many times on here.

No need to rehash it.

There is no prohibition on nm cable in conduit.

There IS a prohibition on stripping the jacket off of nm to use it as individual conductors

 

[bobinyelm]

This dead-horse has been beaten many times on here.

No need to rehash it.

There is no prohibition on nm cable in conduit.

There IS a prohibition on stripping the jacket off of nm to use it as individual conductors

I guess each time a newbe comes upon the question, it starts over again.

Live and learn!

My questions are answered, though, thanks!

Bob